Providing bespoke care nationwide for clients with spinal injuries and neurological conditions
Spinal Muscular Atrophy (SMA) is a degenerative neuromuscular disorder which affects around 1 to 2 out of every 100 000[i] people worldwide. It affects the nerves which send messages between the brain and the muscles, causing progressive muscle weakness. SMA does not affect a person’s brain function or their ability to learn and understand, but muscle weakness can make speech more difficult in some cases meaning that special effort and adaptations have to made to help with communication.
SMA is a genetic condition; it is caused by a faulty gene that is passed down from parent to child. SMA is caused by a deficiency in the SMN1 gene – this is the gene that is responsible for making a type of protein that is essential for healthy function of the motor neurons[ii]. The motor neurons are the nerve cells responsible for control of movement. Without healthy motor neurons, we lose the ability to move our muscles. Although SMA is a disease that affects the motor neurons, it is not the same as motor neurone disease.
SMA is described according to the age at which the symptoms begin to appear, the extent of the symptoms, and the effect they have on expected developmental milestones. The effect of SMA can be on a spectrum from person to person, but is grouped broadly into four different types[iii]:
Type 1 SMA begins in infants younger than 6 months. Babies at this age aren’t very mobile but should hit certain developmental milestones as their muscles and deliberate movement control develop. Babies with SMA 1 do not develop the ability to sit without support, and they can have difficulty breathing and feeding because of weakness in the muscles of the chest. Type 1 SMA is the most severe form, and significantly limits life expectancy. Most children with type 1 SMA only live a few years, but modern treatments and good nutritional and respiratory support mean that children with SMA have better quality of life within that time. Type 1 SMA is the most common form, and affects around 60% of people with the SMA gene.
The symptoms of type 2 SMA usually begin to be noticeable when children are between 6 and 18 months old. Children with type 2 SMA can sit unaided but cannot walk independently, and they can tire very easily. Muscle weakness can affect breathing and swallowing for some children with type 2 SMA, which can cause complications like chest infections and problems with nutrition and hydration. The outlook for children with SMA 2 is better all the time with modern treatment. The expected lifespan of someone with type 2 SMA varies depending on how severe their symptoms are, particularly how much their breathing and swallow are affected. Children with mild type 2 SMA can have a normal lifespan, with some special care and adaptations.
Type 3 SMA usually appears between 18 months and 3 years of age. Children with type 3a have usually learned to walk, but their carers may notice that their walking strength and balance gets worse over time.
Type 3b SMA appears between the ages of 3 and 18 years. Type 3 SMA typically only affects mobility, not breathing, so does not necessarily impact life expectancy – people with type 3 SMA can expect to have the same length and quality of life as anyone else. In general, the later the symptoms of SMA develop, the less severe they are.
Type 4 SMA describes the adult-onset form of the condition. It progressively affects mobility, but very rarely affects breathing, swallowing, or speech. Type 4 SMA shouldn’t impact on longevity, but people with SMA of any form may need support with some activities of daily living, or adaptations to their environment as the disease progresses.
As most cases of SMA are identified in early childhood, it may be parents, carers, or professionals involved in early childhood care such as health visitors who first raise concerns about physical development. Adolescents and adults who develop SMA later in life may notice some signs of muscle weakness or reduced mobility in themselves.
Symptoms alone are enough to suspect SMA, but a blood test can confirm the diagnosis of spinal muscular atrophy[iv]. There are some other diseases that affect movement control in a similar way, so it’s important to get a definite diagnosis so that doctors can plan the right treatment.
In some cases, doctors can tell more about changes in the muscle by taking a biopsy – this is a small sample of muscle tissue. A local anaesthetic is used to make sure the biopsy isn’t too uncomfortable.
After diagnosis, a child with SMA will have regular check-ups with specialist, and lots of support from healthcare professionals experienced in neuromuscular conditions.
As SMA is a genetic disorder which can be inherited from either parent, options are available for genetic counselling and tests for people who have a family history of SMA and who are looking to start a family. These tests can determine the likelihood of passing on the SMA gene, and healthcare professionals who specialise in genetic counselling can give advice about other options, including using donor eggs or sperm, or having a form of IVF where a couple’s own sperm and egg cells are used and fertilised in laboratory conditions before being implanted back into the womb after testing for SMA.
SMA cannot be cured, but is the subject of ongoing research which is making a huge impact on the length and quality of life people with SMA can expect. Some new genetic treatments work to actually replace the gene that causes the problem, allowing the body to produce its own SMN – the protein that protects the motor neurons and muscle control. Some people with SMA might like to be involved in SMA clinical trials to help develop new treatments.
Children with severe SMA that affects their breathing can have respiratory support at home. If they have some control over their breathing, physiotherapists can teach them and their family how to do breathing exercises to help clear the lungs. In more severe forms of SMA, some people need to have suctioning equipment to remove secretions from the throat. Machines are also available to help people cough if they struggle to clear fluid from their chests. People with very limited control over their own breathing might need to have a machine to help them breathe for some or all of the time[v].
A respiratory consultant and specialist nurses, and physiotherapists can all be involved when people have respiratory complications from SMA. Older children and adults with SMA, and their families or carers can learn to manage breathing aids at home.
Some people with severe forms of SMA can develop difficulties with chewing and swallowing food, meaning they can be at risk of malnutrition or dehydration. There are some different options for managing this, including altering the textures of food and drink to make them easier to chew and swallow. Some people with SMA need to have a feeding tube to meet some or all of their nutritional needs. A speech and language therapist can assess swallowing and give advice on exercises, food textures, and alternatives to oral nutrition. A dietitian can help with finding the best way to manage nutritional needs, whether it’s through dietary supplements or alternative ways to stay nourished and hydrated.
For some people, having a limited ability to exercise means that they’re not burning as many calories as they eat, and putting on too much weight can sometimes be a problem. The amount and types of foods taken needs to be thought about carefully; a healthy diet benefits every part of the body.
Having significantly reduced control over muscles and movement makes some kinds of exercise more difficult or impossible, but staying as active as possible within one’s own limits is very important. Exercise can help to maintain strength in any muscles that aren’t affected by SMA, which in turn can mean better health and more independence. Staying strong and flexible is important, and the kind of deep breathing that we do when we exercise is good for our lungs. Exercises will need to be adapted as symptoms develop and change, and some people find that low impact exercises like swimming or cycling can help with joint pain and improve physical and mental health.
Having limited control over muscular movements can put children and adults with SMA at risk of a range of different issues, and the more severe the symptoms of SMA, the higher the risks of complications. Positional changes and pressure-relieving techniques and equipment are important for people who are at risk of pressure damage (‘bed sores’) when they’re not able to move independently in a chair or bed.
Reduced mobility can cause bowel habits to be less regular. This can often be managed with a good diet, and some medications to help when needed. Being less mobile can also make it harder to get to the toilet on time. Good continence care is an important part of life with any condition that significantly affects movement.
People with milder to moderate symptoms of SMA should be offered support on an individual basis to suit any needs they have. Physiotherapists can recommend, supply and fit equipment to help with mobility including splints, braces, walking frames and wheelchairs. Some people with SMA can develop curvature of the spine, which can be corrected with surgery.
People with SMA will receive input from various different members of a multidisciplinary healthcare team. This can include:
SMA is a degenerative condition, meaning that it gets worse over time. The later in life a person develops SMA, the less severe their symptoms are likely to be. The effect and severity of SMA symptoms varies from person to person, so the best people to ask for advice are the healthcare professionals directly involved. Some people with SMA will be profoundly affected by it, and have very reduced movement and impaired breathing. Others will have only very mild motor control symptoms. The amount of support or adaptations a person with SMA might need has to be tailored to the individual.
Parents of children diagnosed with SMA should be able to access support both online and in person. Having a child diagnosed with any form of SMA can be overwhelming, and there is no right or wrong way to feel about it. Everybody involved has a right to need some help, whether that’s physical, emotional, or otherwise.
[i] Verhaart IEC et al. (2017) Prevalence, incidence and carrier frequency of 5q–linked spinal muscular atrophy – a literature review. Orphanet J Rare Dis 12: 124. https://doi.org/10.1186/s13023-017-0671-8
[iv] Mercuri E et al. (2018) Diagnosis and management of spinal muscular atrophy: Part 1: recommendations for diagnosis, rehabilitation, orthopedic and nutritional care. Neuromuscul Disord 28: 103-115. https://doi.org/10.1016/j.nmd.2017.11.005
[v]Finkel RS et al. (2018) Diagnosis and management of spinal muscular atrophy: Part 2: Pulmonary and acute care; medications, supplements and immunizations; other organ systems; and ethics. Neuromuscul Disord 28: 197-207. https://doi.org/10.1016/j.nmd.2017.11.004